1. Identify the CORRECT Statement Concerning the Solubility of Various Solutes

Solutions Practice-1

1. Identify the CORRECT statement concerning the solubility of various solutes:

a) NaCl would be soluble in the hydrocarbon solvent hexane.
b) CaCl2 would be soluble in water.
c) KCl would be soluble in the hydrocarbon solvent benzene.
d) Hexane and benzene would be immiscible.
e) Alcohols and water are generally immiscible.

2. Under what conditions are the molality and molarity of a solution nearly the same?

a) For all solutions where water is the solvent.
b) For all solutions which are very dilute.
c) For all dilute solutions in which the solvent has a density near 1.0 g/mL.
d) For all solutions in which the solvent has a density near 1.0 g/mL.

3. What is the molarity of a solution in which 50.0 mL of chloroform, CHCl3, are placed in a 100.0 mL volumetric flask and the flask is filled to the mark with acetone? The density of pure CHCl3 is 1.483 g/mL.

a) 6.21 M
b) 0.500 M
c) 5.00 M
d) 4.188 M
e) 0.006 M

4. What is the molality of a urea solution in which 10.0 grams of urea, (NH2)2CO are added to 300.0 mL of water at STP?

a) 0.166 m
b) 5.55 x 10-4 m
c) 33.3 m
d) 3.33 x 10-2 m
e) 0.555 m

5. What is the mole fraction of sulfuric acid in an aqueous solution which is 4.00 M sulfuric acid? The density of the solution is 1.250 g/mL.

a) 0.941
b) 0.0672
c) 0.0625
d) 0.0774

6. A solution has a mole fraction of the nonvolatile solute sucrose of 0.125. The vapor pressure of the pure solvent is 26.0 torr at 25°C. What is the vapor pressure of the solution?

a) 3.25 torr
b) 22.75 torr
c) 26.0 torr
d) 760 torr

7. What would be the freezing point of a 3.00 m aqueous solution of a nonvolatile, nonelectrolyte material? The cryoscopic constant of water is Kf = 1.86 °C/molal.

a) 5.6° C
b) -5.6 °C
c) -3 ° C
d) -1.86 °C

8. A solution was made by dissolving 4.50 grams of a nonvolatile solute in 100.0 grams of acetone. The solution boiled at 56.12 °C. The boiling point of pure acetone is 55.95°C and its Kb = 1.71°C/molal. What is the molecular weight of the unknown solute?

a) 453 g/mol
b) 492 g/mol
c) 2.23 x 105 g/mol
d) 223.5 g/mol

9. Identify the INCORRECT statement below concerning the formation of solutions.

a) The large crystal lattice energy of ionic solids is generally favorable to their solution formation.
b) The entropy change upon mixing generally is a favorable factor for the formation of a solution.
c) An exothermic heat of solution would favor the formation of a solution relative to an endothermic one.
d) The exothermic hydration of ions in water is generally a favorable factor to solution formation.
e) One may generally say that "like dissolves like."

10. Identify the INCORRECT statement below:

a) An endothermic heat of solution for NaCl(aq) implies that its solubility would increase as T increases.
b) Henry's Law relates the pressure of a gas above a liquid to the concentration of dissolved gas.
c) The solubility of a substance always increases when the temperature of solution is increased.
d) Raoult's Law relates the vapor pressure of a liquid to its mole fraction in the solution phase.
e) A colligative property is a physical property of a solution that depends on the number of solute particles, and not their identity.

Solution Practice-2

1. Which of the following is not a colligative property?

a) freezing point depression
b) boiling point elevation
c) solubility
d) vapor pressure lowering

2. Which of the following has the least effect on the solubility of a solid in a liquid solvent?

a) temperature
b) nature of the solvent
c) pressure
d) nature of the solute

3. "The amount of a gas dissolved in a solution is directly proportional to the pressure of the gas above the solution" is:

a) Raoult's law
b) Henry's law
c) an example of osmotic pressure
d) van't Hoff's method

4. The ability of one liquid to dissolve in another is called:

a) hydrophilicity
b) miscibility
c) an expanded solvent
d) the solvation energy

5. The dissolution of salt (NaCl) in water is an unfavorable endothermic process. Dissolution occurs anyway because:

a) the system becomes more ordered.
b) the vapor pressure of the solution decreases.
c) salt is a nonpolar solute, water is a nonpolar solvent.
d) the randomness or entropy of the system increases greatly.

6. Which of the following concentration measures may change in value as the temperature of a solution changes?

a) molality
b) molarity

7. An aqueous solution contains 64.0 g of ethanol (C2H5OH) in 122.0 g of total solution. The mole fraction of ethanol is:

a) 0.301
b) 0.432
c) 0.698
d) 0.205
e) none of these

8. A 10.0 g sample of sucrose (C12H22O11) was dissolved in 200.0 g of water. What is the vapor pressure of this solution at 100° C? (the vapor pressure of pure water at 100° C is 760 torr)

a) 760 torr
b) 758 torr
c) 111 torr
d) 688 torr
e) none of these

9. Calculate the change in vapor pressure (DP) of a solution prepared by dissolving 25.5 g of napthalene (C10H8), which is a nonvolatile solute, in 150.0 g of benzene (C6H6). The vapor pressure of benzene at 20° C is 74.6 torr.

a) 70 torr
b) 7.0 torr
c) 67.4 torr
d) 0.09 torr

10. What mass of ethylene glycol (M.W. = 62.l g/mol) antifreeze must be added to 10.0 liters of water to produce a solution that freezes at -23.3 C degrees. Density of water is lg/ml and Kf = l.86° C/m.

a) 7.8 g
b) 3.4 g
c) 7.8 kg
d) 0.78 kg
e) 78 kg

11. What is the boiling point in C° of a solution of a 2.15 m aqueous solution of glycerol ? (Kb = 0.512° C/m)

a) 101.1
b) 100.2
c) 100
d) 1.1

12. A solution was made by dissolving 3.75 g of a solute in 108.7 g of acetone . The solution boiled at 56.58° C. The boiling point of pure acetone is 55.95° C, and the Kb =1.71° C/m. What is the molecular weight of the solute?

a) 143
b) 105
c) 12.7
d) 93.6